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We only know of one so far.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
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Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
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Prune this down to just the struct kvm_irqfd so we can avoid
changing function definition for every flag or field we use.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
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* 'fixes' of git://github.com/hzhuang1/linux:
ARM: pxa: hx4700: Fix basic suspend/resume
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The Microsoft LifeChat 3000 USB headset was causing a very reproducible
hang whenever it was plugged in. At first, I thought the host
controller was producing bad transfer events, because the log was filled
with errors like:
xhci_hcd 0000:00:14.0: ERROR Transfer event TRB DMA ptr not part of current TD
However, it turned out to be an xHCI driver bug in the ring expansion
patches. The bug is triggered When there are two ring segments, and a
TD that ends just before a link TRB, like so:
______________ _____________
| | ---> | setup TRB B |
______________ | _____________
| | | | data TRB B |
______________ | _____________
| setup TRB A | <-- deq | | data TRB B |
______________ | _____________
| data TRB A | | | | <-- enq, deq''
______________ | _____________
| status TRB A | | | |
______________ | _____________
| link TRB |--------------- | link TRB |
_____________ <--- deq' _____________
TD A (the first control transfer) stalls on the data phase. That halts
the ring. The xHCI driver moves the hardware dequeue pointer to the
first TRB after the stalled transfer, which happens to be the link TRB.
Once the Set TR dequeue pointer command completes, the function
update_ring_for_set_deq_completion runs. That function is supposed to
update the xHCI driver's dequeue pointer to match the internal hardware
dequeue pointer. On the first call this would work fine, and the
software dequeue pointer would move to deq'.
However, if the transfer immediately after that stalled (TD B in this
case), another Set TR Dequeue command would be issued. That would move
the hardware dequeue pointer to deq''. Once that command completed,
update_ring_for_set_deq_completion would run again.
The original code would unconditionally increment the software dequeue
pointer, which moved the pointer off the ring segment into la-la-land.
The while loop would happy increment the dequeue pointer (possibly
wrapping it) until it matched the hardware pointer value.
The while loop would also access all the memory in between the first
ring segment and the second ring segment to determine if it was a link
TRB. This could cause general protection faults, although it was
unlikely because the ring segments came from a DMA pool, and would often
have consecutive memory addresses.
If nothing in that space looked like a link TRB, the deq_seg pointer for
the ring would remain on the first segment. Thus, the deq_seg and the
software dequeue pointer would get out of sync.
When the next transfer event came in after the stalled transfer, the
xHCI driver code would attempt to convert the software dequeue pointer
into a DMA address in order to compare the DMA address for the completed
transfer. Since the deq_seg and the dequeue pointer were out of sync,
xhci_trb_virt_to_dma would return NULL.
The transfer event would get ignored, the transfer would eventually
timeout, and we would mistakenly convert the finished transfer to no-op
TRBs. Some kernel driver (maybe xHCI?) would then get stuck in an
infinite loop in interrupt context, and the whole machine would hang.
This patch should be backported to kernels as old as 3.4, that contain
the commit b008df60c6369ba0290fa7daa177375407a12e07 "xHCI: count free
TRBs on transfer ring"
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Andiry Xu <andiry.xu@amd.com>
Cc: stable@vger.kernel.org
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The host controller port status register supports CAS (Cold Attach
Status) bit. This bit could be set when USB3.0 device is connected
when system is in Sx state. When the system wakes to S0 this port
status with CAS bit is reported and this port can't be used by any
device.
When CAS bit is set the port should be reset by warm reset. This
was not supported by xhci driver.
The issue was found when pendrive was connected to suspended
platform. The link state of "Compliance Mode" was reported together
with CAS bit. This link state was also not supported by xhci and
core/hub.c.
The CAS bit is defined only for xhci root hub port and it is
not supported on regular hubs. The link status is used to force
warm reset on port. Make the USB core issue a warm reset when port
is in ether the 'inactive' or 'compliance mode'. Change the xHCI driver
to report 'compliance mode' when the CAS is set. This force warm reset
on the root hub port.
This patch should be backported to stable kernels as old as 3.2, that
contain the commit 10d674a82e553cb8a1f41027bb3c3e309b3f6804 "USB: When
hot reset for USB3 fails, try warm reset."
Signed-off-by: Stanislaw Ledwon <staszek.ledwon@linux.intel.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Acked-by: Andiry Xu <andiry.xu@amd.com>
Cc: stable@vger.kernel.org
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While we are resolving directory modifications in the
tree log, we are triggering delayed metadata updates to
the filesystem btrees.
This commit forces the delayed updates to run so the
replay code can find any modifications done. It stops
us from crashing because the directory deleltion replay
expects items to be removed immediately from the tree.
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
cc: stable@kernel.org
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We can race with unlink and not actually be able to do our igrab in
btrfs_add_ordered_extent. This will result in all sorts of problems.
Instead of doing the complicated work to try and handle returning an error
properly from btrfs_add_ordered_extent, just hold a ref to the inode during
writepages. If we cannot grab a ref we know we're freeing this inode anyway
and can just drop the dirty pages on the floor, because screw them we're
going to invalidate them anyway. Thanks,
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
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The tree log stuff can have allocated space that we end up having split
across a bitmap and a real extent. The free space code does not deal with
this, it assumes that if it finds an extent or bitmap entry that the entire
range must fall within the entry it finds. This isn't necessarily the case,
so rework the remove function so it can handle this case properly. This
fixed two panics the user hit, first in the case where the space was
initially in a bitmap and then in an extent entry, and then the reverse
case. Thanks,
Reported-and-tested-by: Shaun Reich <sreich@kde.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
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When we're evicting an inode during log recovery, we need to ensure that the inode
is not in orphan state any more, which means inode's run_time flags has _no_
BTRFS_INODE_HAS_ORPHAN_ITEM. Thus, the BUG_ON was triggered because of a wrong
check for the flags.
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
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We used the wrong ioctl macro for the getflags ioctl before.
As we don't have the set/getflags ioctls in the user space ioctl.h
at the moment, it's safe to fix it now.
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Alexander Block <ablock84@googlemail.com>
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This introduces btrfs_resume_balance_async(), which, given that
restriper state was recovered earlier by btrfs_recover_balance(),
resumes balance in btrfs-balance kthread.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
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Fix a bug that triggered asserts in btrfs_balance() in both normal and
resume modes -- restriper state was not properly restored on read-only
mounts. This factors out resuming code from btrfs_restore_balance(),
which is now also called earlier in the mount sequence to avoid the
problem of some early writes getting the old profile.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
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Miao pointed out there's a problem with mixing dio writes and buffered
reads. If the read happens between us invalidating the page range and
actually locking the extent we can bring in pages into page cache. Then
once the write finishes if somebody tries to read again it will just find
uptodate pages and we'll read stale data. So we need to lock the extent and
check for uptodate bits in the range. If there are uptodate bits we need to
unlock and invalidate again. This will keep this race from happening since
we will hold the extent locked until we create the ordered extent, and then
teh read side always waits for ordered extents. There was also a race in
how we updated i_size, previously we were relying on the generic DIO stuff
to adjust the i_size after the DIO had completed, but this happens outside
of the extent lock which means reads could come in and not see the updated
i_size. So instead move this work into where we create the extents, and
then this way the update ordered i_size stuff works properly in the endio
handlers. Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
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It is normal behaviour of the low level btrfs function btrfs_map_bio()
to complete a bio with -EIO if the device is missing, instead of just
preventing the bio creation in an earlier step.
This used to cause I/O statistic read error increments and annoying
printk_ratelimited messages. This commit fixes the issue.
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Reported-by: Carey Underwood <cwillu@cwillu.com>
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If the nohz= boot parameter disables nohz, then RCU_FAST_NO_HZ needs to
also disable itself. This commit therefore checks for tick_nohz_enabled
being zero, disabling rcu_prepare_for_idle() if so. This commit assumes
that tick_nohz_enabled can change at runtime: If this is not the case,
then a simpler approach suffices.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Commit d8169d4c (Make __kfree_rcu() less dependent on compiler choices)
created a macro out of an inline function in order to avoid build
breakage for certain combinations of gcc flags. Unfortunately, it also
converted a kfree_call_rcu() to a call_rcu(), which made the rcu_data
structure's ->qlen_lazy field lose counts. This commit therefore changes
the call_rcu() back to kfree_call_rcu().
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Currently, if several CPUs in the same package have all lazy RCU
callbacks, their wakeups will be uncorrelated. If all the CPUs are in the
same power domain (as is often the case), this will result in unnecessary
power-ups of the package. This commit therefore uses round_jiffies()
to round the timeouts to a second boundary, increasing the odds that
they can be coalesced with each other or with other timeouts.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The TINY_PREEMPT_RCU() function rcu_preempt_needs_cpu(), which is called
from rcu_needs_cpu(), assumes that it is in a quiescent state with respect
to the CPU. This is no longer the case. This commit therefore updates
rcu_preempt_needs_cpu() to make it aware that it is not running in a
quiescent state.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: Pascal Chapperon <pascal.chapperon@wanadoo.fr>
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Problems in RCU idle entry and exit are almost always confined to the
offending CPU. This commit therefore switches ftrace_dump() from
DUMP_ALL to DUMP_ORIG.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: Pascal Chapperon <pascal.chapperon@wanadoo.fr>
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If a CPU goes offline with callbacks queued, those callbacks might be
indefinitely postponed, which can result in a system hang. This commit
therefore inserts warnings for this condition.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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It is time to optimize CONFIG_TREE_PREEMPT_RCU's synchronize_rcu()
for uniprocessor optimization, which means that rcu_blocking_is_gp()
can no longer rely on RCU read-side critical sections having disabled
preemption. This commit therefore disables preemption across
rcu_blocking_is_gp()'s scan of the cpu_online_mask.
(Updated from previous version to fix embarrassing bug spotted by
Wu Fengguang.)
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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An uninitialized string may be displayed at the end of the rcu_preempt
detected stall info such as
0: (1 GPs behind) idle=075/140000000000000/0 =8?^D=8?^D
^^^^^^^^^^
if CONFIG_RCU_FAST_NO_HZ is not defined.
This trivial patch clears the string in this case.
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The rcu_is_cpu_idle() function is used if CONFIG_DEBUG_LOCK_ALLOC,
but TINY_RCU defines it only when CONFIG_PROVE_RCU. This causes
build failures when CONFIG_DEBUG_LOCK_ALLOC=y but CONFIG_PROVE_RCU=n.
This commit therefore adjusts the #ifdefs for rcu_is_cpu_idle() so
that it is defined when CONFIG_DEBUG_LOCK_ALLOC=y.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The __call_rcu() function is a bit overweight, so this commit splits
it into actual enqueuing of and accounting for the callback (__call_rcu())
and associated RCU-core processing (__call_rcu_core()).
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The __call_rcu() function will invoke the RCU core, for example, if
it detects that the current CPU has too many callbacks. However, this
can happen on an offline CPU that is on its way to the idle loop, in
which case it is an error to invoke the RCU core, and the excess callbacks
will be adopted in any case. This commit therefore adds checks to
__call_rcu() for running on an offline CPU, refraining from invoking
the RCU core in this case.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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Although __call_rcu() is handled correctly when called from a momentary
non-idle period, if it is called on a CPU that RCU believes to be idle
on RCU_FAST_NO_HZ kernels, the callback might be indefinitely postponed.
This commit therefore ensures that RCU is aware of the new callback and
has a chance to force the CPU out of dyntick-idle mode when a new callback
is posted.
Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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Commit d8169d4c (Make __kfree_rcu() less dependent on compiler choices)
added cpp macro versions of __kfree_rcu() and __is_kfree_rcu_offset(),
but failed to remove the old inline-function versions. This commit does
this cleanup.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The CONFIG_TREE_PREEMPT_RCU and CONFIG_TINY_PREEMPT_RCU versions of
__rcu_read_lock() and __rcu_read_unlock() are identical, so this commit
consolidates them into kernel/rcupdate.h.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The return value from rcu_assign_pointer() is not used, and using it
would be quite ugly, for example:
q = rcu_assign_pointer(global_p, p);
To prevent this sort of ugliness from spreading, this commit wraps
rcu_assign_pointer() in a do-while loop.
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reported-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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This commit removes the extraneous parentheses from rcu_assign_keypointer()
so that rcu_assign_pointer() can be wrapped in do-while. It also wraps
rcu_assign_keypointer() in a do-while and parenthesizes its final argument,
as suggested by David Howells.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The return value from RCU_INIT_POINTER() is not used, and using it
would be quite ugly, for example:
q = RCU_INIT_POINTER(global_p, p);
To prevent this sort of ugliness from appearing, this commit wraps
RCU_INIT_POINTER() in a do-while loop.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: David Howells <dhowells@redhat.com>
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This commit applies the INIT_RCU_POINTER() macro to all uses of
RCU_POINTER_INITIALIZER() that were all too cleverly creating gcc-style
initializations.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: David Howells <dhowells@redhat.com>
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RCU_INIT_POINTER() returns a value that is never used, and which should
be abolished due to terminal ugliness:
q = RCU_INIT_POINTER(global_p, p);
However, there are two uses that cannot be handled by a do-while
formulation because they do gcc-style initialization:
RCU_INIT_POINTER(.real_cred, &init_cred),
RCU_INIT_POINTER(.cred, &init_cred),
This usage is clever, but not necessarily the nicest approach.
This commit therefore creates an RCU_POINTER_INITIALIZER() macro that
is specifically designed for gcc-style initialization.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: David Howells <dhowells@redhat.com>
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The _rcu_barrier() function accesses other CPUs' rcu_data structure's
->qlen field without benefit of locking. This commit therefore adds
the required ACCESS_ONCE() wrappers around accesses and updates that
need it.
ACCESS_ONCE() is not needed when a CPU accesses its own ->qlen, or
in code that cannot run while _rcu_barrier() is sampling ->qlen fields.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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There are a couple of open-coded initializations of the rcu_data
structure's RCU callback list. This commit therefore consolidates
them into a new init_callback_list() function.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The code that attempts to identify stalls that end just as we detect
them is broken by both flavors of initialization failure. This commit
therefore properly initializes and computes the count of the number
of reasons why the RCU grace period is stalled.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The current rcutorture rcu_barrier() testing never intentionally runs
more than one instance of rcu_barrier() at a given time. This fails
to test the the shiny new concurrency features of rcu_barrier(). This
commit therefore modifies the rcutorture fakewriter kthread to randomly
invoke rcu_barrier() rather than the usual synchronize_rcu().
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The rcu_torture_barrier() function has a copy-and-paste typo in the
string passed to rcutorture_shutdown_absorb(), which this commit fixes.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The child threads in the rcu_torture_barrier_cbs() are improperly
synchronized, which can cause the rcu_barrier() tests to hang. The
failure mode is as follows:
1. CPU 0 running in rcu_torture_barrier() sets barrier_cbs_count
to n_barrier_cbs.
2. CPU 1 running in rcu_torture_barrier_cbs() wakes up, posts
its RCU callback, and atomically decrements barrier_cbs_count.
Because barrier_cbs_count is not zero, it does not do the wake_up().
3. CPU 2 running in rcu_torture_barrier_cbs() wakes up, but
finds that barrier_cbs_count is not equal to n_barrier_cbs,
and so returns to sleep.
4. The value of barrier_cbs_count therefore never reaches zero,
which causes the test to hang.
This commit therefore uses a phase variable to coordinate the test,
preventing this scenario from occurring.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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SRCU now has a call_srcu() and an srcu_barrier(), but rcutorture does not
test them. This commit adds the machinery to allow rcutorture's existing
tests for call_rcu() and rcu_barrier() to apply to the SRCU equivalents.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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Move the raw SRCU interfaces out of the middle of the normal SRCU
interfaces.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The advent of call_srcu() and srcu_barrier() obsoleted some of the
documentation, so this commit brings that up to date.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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Before RCU had unified idle, the RCU_SAVE_DYNTICK leg of the switch
statement in force_quiescent_state() was dead code for CONFIG_NO_HZ=n
kernel builds. With unified idle, the code is never dead. This commit
therefore removes the "if" statement designed to make gcc aware of when
the code was and was not dead.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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This commit applies the new for_each_rcu_flavor() macro to the
kernel/rcutree_trace.c file.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The arrival of TREE_PREEMPT_RCU some years back included some ugly
code involving either #ifdef or #ifdef'ed wrapper functions to iterate
over all non-SRCU flavors of RCU. This commit therefore introduces
a for_each_rcu_flavor() iterator over the rcu_state structures for each
flavor of RCU to clean up a bit of the ugliness.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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With the advent of __this_cpu_ptr(), it is no longer necessary to pass
both the rcu_state and rcu_data structures into __rcu_process_callbacks().
This commit therefore computes the rcu_data pointer from the rcu_state
pointer within __rcu_process_callbacks() so that callers can pass in
only the pointer to the rcu_state structure. This paves the way for
linking the rcu_state structures together and iterating over them.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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This commit adds an rcubarrier file to RCU's debugfs statistical tracing
directory, providing diagnostic information on rcu_barrier().
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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This commit adds event tracing for _rcu_barrier() execution. This
is defined only if RCU_TRACE=y.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
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The traditional rcu_barrier() implementation has serialized all requests,
regardless of RCU flavor, and also does not coalesce concurrent requests.
In the past, this has been good and sufficient.
However, systems are getting larger and use of rcu_barrier() has been
increasing. This commit therefore introduces a counter-based scheme
that allows _rcu_barrier() calls for the same flavor of RCU to take
advantage of each others' work.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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